The present invention relates to a method of assuring authenticity of electronically-generated data.
Conventionally, electronic signature technologies (also referred to as digital signatures) provide methods of assuring authenticity of electronically-generated data (See, for example, Bruce Schneier, Applied Cryptography: Protocols, Algorithms, and Source Code in C, Second Edition, John Wiley & Sons, (Oct. 18, 1995), pp. 483-502 (hereinafter, referred to as Document 1)).
Also, the following techniques are known, i.e., a technique in which a part of a document permitted by a signer can be deleted from a previously-signed document owned by an owner different from the signer, and the validity of the signed document after the deletion can be confirmed (see, for example, Ron Steinfeld, Laurence Bull and Yuliang Zheng, “Content Extyraction Signatures”, in International Conference on Information Security and Cryptology ICISC 2001, volume 2288 of LNCS, pp. 285-304, Berlin, 2001, Springer-Verlag (hereinafter, referred to as Document 2)), and an electronic data authenticity assurance technique in which both assurance of authenticity of a disclosed document and deletion of information unsuitable for disclosure are possible (see, for example, US Patent Application Laid-Open No. 2005/0015600 (hereinafter, referred to as Document 3)).